anomaly vs abnormalcy

anomaly and abnormalcy both are nouns.

Word	Noun	Adjective	Verb	Adverb
anomaly	Yes	No	No	No
abnormalcy	Yes	No	No	No

As nouns, abnormalcy is a hypernym of anomaly; that is, abnormalcy is a word with a broader meaning than anomaly:

anomaly: deviation from the normal or common order or form or rule
abnormalcy: an abnormal physical condition resulting from defective genes or developmental deficiencies

Other hypernyms of anomaly include abnormality.

anomaly (noun)	abnormalcy (noun)
(astronomy) position of a planet as defined by its angular distance from its perihelion (as observed from the sun)	an abnormal physical condition resulting from defective genes or developmental deficiencies
a person who is unusual
deviation from the normal or common order or form or rule